Flashcards in CHEMICAL BONDING AND STRUCTURE Deck (88)
strong electrostatic attraction between the nuclei of metal cations and delocalised electrons.
high thermal/electrical conductivity
Why do metals have high mp's?
Need to break strong forces of attraction between the cation nuclei and delocalised electrons.
also giant lattice structure requires much energy to break
What determines bp/mp's?
no. of delocalised electrons (group 1 is low while d-block metals are higher)
size of cation (smaller radii has closer electrons to nuclei higher mp)
electrical conductivity in metals
movement of delocalised electrons towards the positive terminal of a cell with a potential difference.
delocalised electrons passing KE along metal.
ability to draw metal into a wire
what does ductility and malleability depend on?
the cation and electron movement ability. layers slide over one another and delocalised electrons prevent strong forces of repulsion between cations.
strong electrostatic attraction between oppositely charged ions.
arrangement of ionic substances
giant ionic lattice in which electrostatic attraction occurs in all directions.
how do you determine the strength of electrostatic attractions in an ionic substance?
calculation of energy per mole of solid needed to separate ions to infinity in which ions can no longer interact
how is strength of ionic bonding affected by size of cation?
as cation size increases, amount of energy needed to separate them decreases
how is strength of ionic bonding affected by size of anion?
increases as anion size increases
how does size of ions affect energy needed to separate ionic substances to infinity?
smaller substances require more energy to separate
why must data of ionic radii all come from the same source?
because radii is difficult to measure and several methods could conflict in accuracy.
properties of ionic substances
poor electrical conductivity as a solid
why do ionic substances have high melting points?
giant lattice networks of oppositely charged ions have combined large electrostatic forces.
why are ionic substances brittle?
as stress causes ionic layers to slide over one another, meaning same charge ions are next to each other, repelling
why are ionic substances water soluble
polarity of water molecues allows separation of ions
reason for electrical conductivity when molten
previously fixed electrons become mobile, allowing a migration of electrons towards the positive terminal
what sort of current is used in electrolysis
2 atoms overlapping atomic orbitals of which contain a singular electron
3 ways covalent bonds interact
sigma (2 s orbitals)
sigma (2 P orbitals)
pi (2 P orbitals)
how may pi orbitals form? how does this affect the molecule?
sigma bonds may lead to the formation of pi bonds, creating larger electron density above and below the molecule
the distance between nuclei of 2 atoms covalently bonded.
how does bond length affect covalent bond strength
shorter length, greater strength
the ability of an atom to attract a bonding pair of electrons.
how does electronegativity change over the periodic table?
decreases down groups
increases across periods